1. Field of the Invention
The present invention relates to an image forming apparatus including an image scanning unit of an electronic copying machine in an upper portion of a machine body, and particularly to improvements to a mounting structure of a platen cover that opens and closes a document scanning surface of the image scanning unit.
2. Description of the Related Art
In the present invention, the platen covers having different specifications are mounted on the machine body of the same image forming apparatus. This technique is already disclosed in a publicly-known document. In the publicly-known document, a sensor unit can be shared among the platen covers in order to sense a closing angle of the platen cover, even if the platen covers having different specifications are mounted on the machine body. The closing angle of the platen cover, sensed with the sensor unit, can be set to the same angle. In the publicly-known document, specific examples of the platen covers having different specifications include a platen cover that serves only to hold a document and a platen cover that has a function of editing a scanned image in addition to the function of holding the document.
When at least two kinds of platen covers having different weights are mounted on the same machine body, i.e., due to the presence or absence of the function of editing the scanned image or the presence or absence of the automatic document feeder, conventionally it is necessary to change a support structure for supporting the platen cover. Specifically, conventionally the support structure is changed by exchanging the metallic support frame that supports a platen cover attaching unit. Therefore, the exchange of the support frame becomes troublesome, and it is difficult to efficiently perform the mounting work or exchange work of the platen cover. Thus, there is a demand for establishing a mounting structure in which the mounting work or exchange work of the platen cover can be performed efficiently and rapidly without exchanging the support frame.
Further, in the conventional image forming apparatus, it is necessary to develop a whole structure of the machine body such that the support frame can be exchanged, which results in a problem in that a degree of design freedom of the whole apparatus decreases. Moreover, it is necessary to design and prepare a plurality of kinds of frames, and the number of components is inevitably increased, which results in a problem in that the overall cost of the image forming apparatus increases.